Armor & Mobility

AUG 2017

Military magazines in the United States and Canada, covering Armor and Mobility, focuses on tactical vehicles, C4ISR, Special Operations Forces, latest soldier equipment, shelters, and key DoD programs

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U.S. Army Yuma Proving Ground (YPG) is well known for testing
virtually every piece of equipment in the ground combat arsenal. The
fruits of this testing include better and longer lasting equipment, as
well as the ability to multiply a ground force more rapidly.
Prior to the first Gulf War in the early 1990's, the life-expectancy
of the tracks used to propel an M1 Abrams Main Battle Tank along
the ground was measured in the hundreds of miles. After extensive
testing at U.S. Army Yuma Proving Ground, today's tank treads last for
thousands of miles.
Mitigating the Turbulence to Chute Threat
A more recent example of this high-impact, long-term testing is
studies the proving ground's Air Combat Systems Test Directorate
have conducted on the C-17 Globemaster to determine the heaviest
weight the aircraft can safely carry. A follow-on study has looked at
the amount of time and distance necessary between each element of
a multi-element insertion of combat parachutists, known tactically as
a mass exit insertion of the Global Response Force (GRF).
As air behaves like a fluid, the air disturbance left by massive cargo
aircraft speeding through the sky is extremely turbulent and fast. The
shedding of high and low pressures required for lift rolls up near the
aircraft wing tips, result in powerful vortices that can remain over the
drop zone for several minutes.
"It is very violent," said Keith Allen, team lead in the Aviation
Systems and Electronic Test Division. "We're talking 150 to 200
feet per second in tangential velocity. It would definitely collapse a
parachute if you got caught up in it."
The wings of military cargo planes are equipped with specially
shaped finlets to help dissipate this vortex, but the extreme turbulence
is still invisible and not able to be completely eliminated. As a result,
formations of C-17s carrying jumpers are required to keep a minimum
distance from each other: if this distance could be safely shortened,
more airborne Soldiers could reach the ground and enter a battle
faster.
"The current spacing is based on a very conservative approach
to ensure, in all conditions, that the vortices are dissipated or have
moved off the drop zone in time for the next element of jumpers," said
A U.S. Army Yuma Proving Ground study could lead to faster, more precise mass parachute drops.
By Mark Schauer, YPG Public Affairs
TAMING THE DROP ZONE
Airborne Soldiers participating in a mass insertion must contend with a roiling aerial
sea caused by the backwash of massive cargo airplanes speeding through the air.
Testers at U.S. Army Yuma Proving Ground have conducted an ambitious study of the
life cycle of these aerial disturbances in an effort to reduce the amount of distance
required between planes participating in a mass jump. (U.S. Army Photo)
ENHANCING RE-SUPPLY LOGISTICS AIR DROP PRECISION
www.tacticaldefensemedia.com 22 | Armor & Mobility | August 2017